Respirable Crystalline Silica
Crystalline Silica as explained by OSHA:
Crystalline Silica is a common mineral found in the earth's crust. Materials like sand, stone, concrete, and mortar contain crystalline silica. Silica can also be used to make products such as glass, pottery, ceramics, bricks, and artificial stone.
Respirable Crystalline Silica is described as exceedingly small particles at least 100 times smaller than ordinary sand you might find on beaches and playgrounds.
